Доступ предоставлен для: Guest
Главная ICHMT DL Текущий год Архив Исполнительный Комитет ICHMT

Investigation of local turbulent heat transport in Rayleigh-Benard convection by means of DNS and LES

DOI: 10.1615/ICHMT.2006.TurbulHeatMassTransf.1040
pages 503-506

Olga Shishkina
DLR - Institute for Aerodynamics and Flow Technology, Bunsenstrasse 10, 37073 Göttingen, Germany

Claus Wagner
German Aerospace Center (DLR), Institute for Aerodynamics and Flow Technology, Bunsenstrasse 10, 37073 Göttingen, Germany; Ilmenau University of Technology, Institute of Thermodynamics and Fluid Mechanics, Germany


Vertical heat flux Ω in turbulent Rayleigh-Benard convection [1],[2] is studied based on data obtained in Direct Numerical Simulations (DNS) for Rayleigh numbers Ra = 106 and 107 and Large-Eddy Simulation (LES) for Ra = 108. The well resolved LES uses the tensor-diffusivity model [3] together with the top-hat filter. In all simulations the Prandlt number and the aspect ratio of the cylindrical container are Pr = 0.7 and Γ = 5, respectively.
An analysis of the spatial distribution of the vertical heat flux shows that the volume of the fluid with negative Ω-values increases with the Rayleigh number and fills out one third of the total volume for Ra = 108. With growing Ra the zones with high values of the mean local heat flux (averaged in time and in azimuthal direction) nestle closer to the corners, where the horizontal and vertical walls intersect. For the considered Rayleigh numbers and Γ = 5 it is shown that the portion of the whole domain, in which the thermal dissipation rate is relatively small, increases with Ra. Earlier a similar result was obtained for Γ = 10 [4]. These observations support the conjecture by Grossmann and Lohse [2] that the background part of the thermal dissipation rate increases with the Rayleigh number.

ICHMT Digital Library

Bow shocks on a jet-like solid body shape. Thermal Sciences 2004, 2004. Pulsed, supersonic fuel jets - their characteristics and potential for improved diesel engine injection. PULSED, SUPERSONIC FUEL JETS - THEIR CHARACTERISTICS AND POTENTIAL FOR IMPROVED DIESEL ENGINE INJECTION
View of engine compartment components (left). Plots of temperature distributions in centreplane, forward of engine (right). CHT-04 - Advances in Computational Heat Transfer III, 2004. Devel... DEVELOPMENT AND CURRENT STATUS OF INDUSTRIAL THERMOFLUIDS CFD ANALYSIS
Pratt & Whitney's F-135 Joint Strike Fighter Engine under test in Florida is a 3600F class jet engine. TURBINE-09, 2009. Turbine airfoil leading edge stagnation aerodynamics and heat transfe... TURBINE AIRFOIL LEADING EDGE STAGNATION AERODYNAMICS AND HEAT TRANSFER - A REVIEW
Refractive index reconstructed field. (a) Second iteration. (b) Fourth iteration. Radiative Transfer - VI, 2010. Theoretical development for refractive index reconstruction from a radiative ... THEORETICAL DEVELOPMENT FOR REFRACTIVE INDEX RECONSTRUCTION FROM A RADIATIVE TRANSFER EQUATION-BASED ALGORITHM
Two inclusion test, four collimated sources. Radiative Transfer - VI, 2010. New developments in frequency domain optical tomography. Part II. Application with a L-BFGS associated to an inexa... NEW DEVELOPMENTS IN FREQUENCY DOMAIN OPTICAL TOMOGRAPHY. PART II. APPLICATION WITH A L-BFGS ASSOCIATED TO AN INEXACT LINE SEARCH